Dewaxing solvent

Solvent dewaxing is a chemical separation process in which no chemical reactions occur. Therefore the composition of the dewaxed oil is completely dependent on that of the waxy feed and represents the subtraction of the wax composition. Solvent dewaxing works because it exhibits a preference to crystallize out the highest carbon number n-paraffins, followed by isoparaffins and 

FIGURE 6.5 Simplified flow diagram toluene/MEK dewaxing. 

Source S. Marple and L. J. Landry, Modern Dewaxing Technology in Advances in Petroleum Chemistry and Refining, vol. X, Ed., J.J. McKetta, Jr., Interscience, 1965. With permission. 

FIGURE 6.7 Normal and non-normal paraffin distributions in a waxy 100N feed to dewaxing. Source R. J. Taylor and A. J. McCormack, Study of Solvent and Catalytic Lube Oil Dewaxing by Analysis of Feedstocks and Products, Ind. Eng. Chem. Res., vol. 31, pp. 1731-1738 (1992). With permission. 

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Lubricants. Petroleum lubricants continue to be the mainstay for automotive, industrial, and process lubricants. Synthetic oils are used extensively in industry and for jet engines they, of course, are made from hydrocarbons. Since the viscosity index (a measure of the viscosity behavior of a lubricant with change in temperature) of lube oil fractions from different cmdes may vary from +140 to as low as —300, additional refining steps are needed. To improve the viscosity index (VI), lube oil fractions are subjected to solvent extraction, solvent dewaxing, solvent deasphalting, and hydrogenation. Furthermore, automotive lube oils typically contain about 12—14% additives. These additives maybe oxidation inhibitors to prevent formation of gum and varnish, corrosion inhibitors, or detergent dispersants, and viscosity index improvers. The United States consumption of lubricants is shown in Table 7. 

Solvent Treatment. Solvent processes can be divided into two main categories, solvent extraction and solvent dewaxing. The solvent used in the extraction processes include propane and cresyHc acid, 2,2 -dichlorodiethyl ether, phenol (qv), furfural, sulfur dioxide, benzene, and nitrobenzene. In the dewaxing process (28), the principal solvents are benzene, methyl ethyl ketone, methyl isobutyl ketone, propane, petroleum naphtha, ethylene dichloride, methylene chloride, sulfur dioxide, and iV-methylpyrroHdinone. 

On the other hand, intermediate paraffin distillates contain paraffin waxes and waxes intermediate in properties between paraffin and microwaxes. Thus, the solvent dewaxing process produces three different slack waxes depending on whether light, intermediate, or heavy paraffin distillate is processed. The slack wax from heavy paraffin distillate may be sold as dark raw wax, the wax from intermediate paraffin distillate as pale raw wax. The latter is treated with lye and clay to remove odor and improve color. 

Another method of separating petrolatum from residua is by centrifuge dewaxing. In this process, the reduced cmde oil is dissolved in naphtha and chilled to —18° C or lower, which causes the wax to separate. The mixture is then fed to a battery of centrifuges where the wax is separated from the Hquid. However, the centrifuge method has been largely displaced by solvent dewaxing methods as well as more modem methods of wax removal. Similar use is... 

Lubricating Oil Manufacture This consists of solvent deasphalting, phenol treating, and solvent dewaxing. In dewaxing, waxy lube is diluted with a solvent such as propane or methyl ethyl ketone (MEK), and cooled to crystallize the wax which is then removed by filtration. 

Solvent dewaxing, 13 662, 670 Solvent dyeing, 9 160, 204, 243 Solvent effects, 23 96... 

Solvent dewaxing Treatment Cool/filter Remove wax from Inbe stocks Vacuum tower lube oils Dewaxed lube base stock... 

Solvent dewaxing (Figure 3.14), in which the feedstock is mixed with one or more solvents, then the mixture is cooled down to allow the formation of wax crystals, and the solid phase is separated from the liquid phase by filtration. 

The major solvent refining processes include solvent deasphalting, solvent dewaxing, lube oil solvent refining, aromatic extraction, and butadiene extraction. These processes are briefly described below. 

Solvent dewaxing removes wax from lubricating oil stocks, promoting crystallization of the wax. Solvents include furfural, phenol, cresylic acid-propane (DuoSol), liquid sulfur dioxide (Eleleanu process), B,B-dichloroethyl ether, methyl ethyl ketone, nitrobenzene, and sulfur-benzene. The process yields de-oiled waxes, wax-free lubricating oils, aromatics, and recovered solvents. 

The first commercial installation employing special organic solvents in dewaxing was made by the Indian Refining Co. in 1927 (32). The process as originally used employed a mixture of acetone and benzene as the special solvents, based on the inventions of F. X. Govers. The process as further developed employs a mixture of methyl ethyl ketone and aromatic solvents such as benzene and toluene. It is known as the solvent dewaxing process. 

The wax cake obtained from paraffin-distillate solvent dewaxing sweats more readily than that obtained from pressing, because the former has less oil. The amorphous wax recovered from the more viscous oils will not sweat, and therefore solvent processes for deoiling ljiave to be installed. These usually involve a repulping or resolution of the wax in... 

Figure 13. Chromatogram of solvent-dewaxed oil from Cie-Clt wax distillate...

MEK dewaxing a continuous solvent dewaxing process in which the solvent is generally a mixture of methyl ethyl ketone and toluene. 

Solvent dewaxing a process for removing wax from oils by means of solvents usually by chilling a mixture of solvent and waxy oil, filtration or by centrifuging the wax which precipitates, and solvent recovery. 

Figure 5.28 Simplified flow schemes of (a) a conventional and (b) Mobil Oil s membrane solvent dewaxing processes. Refrigeration economizers are not shown. The first 3 million gallon/day commercial unit was installed at Mobil s Beaumont refinery in 1998. Polyimide membranes in spiral-wound modules were used [41-43]...

Paraffin wax from a solvent dewaxing operation is commonly known as slack wax, and the processes employed for the production of waxes are aimed at deoiling the slack wax (petroleum wax concentrate). 

B A solvent dewaxing unit in an oil refinery is separating 3000 bbl/day of a lubricating... 

Depending upon the specific needs, conventional plants may be converted to hybrid plants to improve capacity and/or product quality. An example of a hybrid configuration is used by Shell to manufacture their XHVI. In this particular case, the plant couples a lube hydrocracker with a solvent dewaxing unit. There are several modifications or improvements of known technologies that can be used as a Mix and Match to Needs to upgrade existing plants. 

As mentioned earlier, base oils are required to meet stringent cold flow properties, such as pour point and cloud point. This is achieved by dewaxing of the base oil, i.e. by removing the high molecular weight linear paraffins as done by solvent dewaxing. More recent approaches have been centered on the use of catalysts, particularly the use of zeolitic catalytic materials. 

It is the complex relationship between the yield of base stock, its VI and its cold flow properties (pour point and/or cloud point) that leads to the differentiation and optimization of selective dewaxing catalysts and processes, where shape selective catalysis is of critical importance. For example, Figure 8.10 shows the advantages of MSDW-2 over earlier technologies such as solvent dewaxing and MSDW-1 (25). 

Scholten G.G., Solvent Dewaxing, Encyclopedia of Chemical Processing and Design (Marcel Dekker, inc, New York), 15 (1983) 353-370. 

SDW [Solvent DeWaxing] A general term for processes that remove linear paraffinic hydrocarbons from petroleum fractions by solvent extraction. 

MQV820 CAS 64742-63-8 HR 3 MINERAL OIL, PETROLEUM DISTILLATES, SOLVENT-DEWAXED HEAVY NAPHTHENIC (mild or no solvent-refining or hydrotreatment)... 

SYNS DISTILLATES (PETROLEUM), SOLVENT-DEWAXED HEAVY NAPHTHENIC (9CI) SOLVENT-DEWAXED HEAVY NAPHTHENIC DISTILLATE... 

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